Question

The water level of a lake fell by 1 and one half
inches during a 1 and two thirds
​-week-long dry spell. Find the average rate at which the water level changed every week.

Answer 1

Change = -1 1/2 in = -3/2 in. Time = 1 2/3 wk = 5/3 wk.
Average rate = (-3/2) ÷ (5/3) = (-3/2)·(3/5) = -9/10 in/week.

So the water level fell by 9/10 inch per week (≈ -0.9 in/week).